A heating system with several parallel connected heat exchangers is known from, for example, DE 100 57 361 A1. The heat exchangers are partly made as radiators, partly as heat exchangers for a floor heating system. They are parallel connected, that is, they are supplied from the same source. In the known case, this is a boiler, which feeds an inlet line via a mixing valve.
In a similar manner, the method can also be used for adjusting heat exchangers, which are not serving the heating of a room, but the cooling. While for the heating of a room a fluid is used as heat carrying medium, whose temperature is higher than the temperature of the room to be heated, for example heated water, a corresponding fluid, whose temperature is lower, is used for cooling. However, in principle the problems are the same in both cases.
In the following, the invention is described in connection with a heating system. As mentioned, however, it can also be used for corresponding room cooling. The invention is particularly suited for use with floor heating systems.
In floor heating systems the individual heating circuits provide different flow resistances to the heat carrying medium. In this connection, a heating circuit comprises a heat exchanger with its inlets and outlets, however, distinguishing between the heat exchanger and the inlet often being difficult in floor heating systems. The different flow resistances are, for example caused by the fact that one heating circuit must supply a larger room than another and therefore the pipe in the floor is longer. When two such heating circuits with different resistances report a heat demand at the same time, the larger share of the heat carrying medium will flow into the heating circuit with the smallest resistance. This is unfavourable, as the heating circuit then does not utilise the total heat of the heat carrying medium, which increases the return temperature from this heating circuit. At the same time, the other heating circuit does not get sufficient heat carrying medium, so that here the heat supply is insufficient.
Desired is, however, a behaviour, which ensures that the heating circuit with the larger resistance receives the major share of the heating fluid, whereas the heating circuit with the smaller flow resistance receives a correspondingly smaller share.
In order to achieve this goal, at present a manual adjustment is made during the installation. In some cases, this adjustment is also called “compensation” or “flow limitation”. During this adjustment, the flow resistances of the individual heating circuits, that is, the individual heat exchangers, are changed so that they get a “suitable” hydraulic resistance. When, then, several heating circuits, in the present case two, report the same heat demand, the heating fluid will split up according to the demand.
This method is practised in such case at present. However, it is not always satisfactory. Firstly, each heating circuit needs a throttle, which is accessible from the outside, by means of which the flow resistance can be adjusted. Secondly, a calculation of the setting is required. This is often made in that the flow resistance of the individual heating circuit is calculated. In many cases, such a calculation is not very exact. More exact settings can be made by means of a measuring of the flow resistance or the volume flow through the individual heating circuits. However, this method is relatively expensive. By means of the measured or calculated values, the individual heating circuits must be set.
Additionally, the flow resistance of the individual heating circuits is in many cases only an insufficient criterion for the supply of the individual heating circuits. Also the heat resistance of the floor in a floor heating system or the heat demand of a room can have an influence on the setting. For example, the head demand with a carpeted floor will be different than with a floor tile floor.
A room facing south, which is more frequently exposed to sun radiation, will have a different heat demand than a room on the weather side, for example facing north.